>From experience I find that BTrees are very fast to write to and pick
out items from. Even in the millions. (Never gone into the tens of
millions or further)
Also, when it comes to browsing stuff I find SQL faster and easier to
work with. An added advantage of a RDBMS is that you get the indexing
seamlessly built in (no need to bridge zbrain.getObject()) and it
makes it easier to optimize and figure out which indexes help and
which indexes slow you down which is something that is far from
obvious with a ZCatalog approach.